To modify a child custody agreement in Denver, Colorado, one must demonstrate a significant and ongoing change in circumstances since the last custody order. The process involves filing a motion, potentially undergoing mediation, and attending a court hearing where both parties can present their case. The court will decide on the modification based on the child’s best interests, issuing a new custody order if the changes are justified. It’s important to consult with a custody modification lawyer to ensure the process is handled correctly and in the best interest of the child.